function refresh_captcha(img_id) {
    var img_ins = document.getElementById(img_id);
    
    // get a different num every time, use Date()
    var d = new Date();
    var pars = d.getMilliseconds();
    img_ins.src = ZORPIA_JS_LANG.DOMAIN_CAPTCHA + 'captcha?when=' + pars;
    
    return true;
}

function CheckLogin(this_form)
{
    var i,j,strTemp;
    strTemp="0123456789";
    var NUM = this_form.captcha.value;
    var error_login = document.getElementById("error_login");
 
    // check if cookie enabled
    if (!navigator.cookieEnabled){
        error_login.innerHTML = (ZORPIA_JS_LANG.INVALID_COOKIE) ? ZORPIA_JS_LANG.INVALID_COOKIE : " Please enable cookies for your browser. ";
        return false;
    }
    
    if ( NUM.length != 4){
        error_login.innerHTML = (ZORPIA_JS_LANG.INVALID_CAPTCHA) ? ZORPIA_JS_LANG.INVALID_CAPTCHA  : "Wrong code. The code only consists of 4 numbers.";
        return false;
    }

    for (i=0;i<NUM.length;i++)
    {
        j=strTemp.indexOf(NUM.charAt(i)); 
        if (j==-1)
        {
            // has other character
            error_login.innerHTML = (ZORPIA_JS_LANG.INVALID_CAPTCHA) ? ZORPIA_JS_LANG.INVALID_CAPTCHA : "Wrong code. The code only consists of 4 numbers.";
            return false;
        }
    }
    
    disableForm(this_form);
    return true;
}